A variable valve operating device is conventionally used to vary open and close timings of an intake valve for an internal combustion engine, on a restart of the internal combustion engine or during operation of the internal combustion engine. One configuration of the variable valve operating device is disclosed in Patent Document 1. In an ordinary state where the temperature of the internal combustion engine is not lowered, this prior art variable valve operating device restarts the internal combustion engine with no variation of the close timing of the intake valve set to its most delayed position at a stop time of the internal combustion engine. In a low temperature state where the temperature of the internal combustion engine is lowered, on the other hand, the prior art variable valve operating device restarts the internal combustion engine with an advance of the close timing of the intake valve from its most delayed position. In the ordinary state, such control lowers the inertia supercharging and decreases the compression ratio in the cylinder, thus restricting the potential vibration on the start of the internal combustion engine. In the low temperature state, such control restricts the decrease in compression ratio in the cylinder, thus ensuring startability of the internal combustion engine.
Patent Document 1: Japanese Patent Laid-Open No. 2000-34913